With the development of communications technologies, more and more enterprises deploy a unified communication (UC, unified communication) system based on a voice over IP (Voice over Internet Protocol, VoIP) technology.
In a unified communication service, users of the same enterprise generally own an IP telephone number and a communication account at the same time. IP telephone number portability is an important function of the unified communication service. By using the IP telephone number portability function, a user can use an IP telephone number on different IP telephones, for example, when the user goes to an office location on business, the user can use the IP telephone number on an IP telephone at the office location. In the prior art, a user performs login by using a communication account in a manner of inputting the communication account and password on a communication client, and performs login by using an IP telephone number in a manner of manually inputting the IP telephone number and password on an IP telephone. With the prior art, if a user needs to perform login by using a communication account and an IP telephone number, a manual input manner is required for login, so the operation is complex.